Thailand's Prime Minister Prayuth Chan-ocha, left, and Philippine President Rodrigo Duterte walk together at the government house in Bangkok, Thailand, Tuesday, March 21, 2017. Photo Credit: AP

BANGKOK — Thailand’s prime minister has accepted President Donald Trump’s invitation to visit the United States, his office announced Monday, as the U.S. leader made an unexpected diplomatic initiative toward his Southeast Asian counterparts.

Trump telephoned Thailand’s Prime Minister Prayuth Chan-ocha and Singapore Prime Minister Lee Hsien Loong on Sunday to reaffirm traditional close relations and invite them for meetings. The invitation followed one made in a call late Saturday to Philippine President Rodrigo Duterte.

Washington’s diplomacy in Asia has focused on China and tensions with North Korea, although Vice President Mike Pence included Indonesia on a recent Asia tour.

Prayuth’s office said he had accepted Trump’s invitation, while a Singapore Foreign Ministry statement said the two leaders “looked forward to meeting each other soon.” No dates were mentioned for their visits.

Human rights groups have criticized Prayuth for seizing power in a coup and curbing democratic rights, while Duterte is scorned for his deadly war on drugs. Both bristle at the criticism.

However, Washington has strategic concerns in countering Chinese influence in Southeast Asia. Thailand, Singapore and the Philippines are historically the most pro-Western nations of the region, but China’s influence has been increasing as it flexes its economic muscle and projects its military power into the South China Sea.

Prayuth’s government last week announced approval of its navy’s plan to purchase a submarine from China, the latest move in diversifying its military suppliers, traditionally from the United States

Monday’s statement from Prayuth’s office said he and Trump reaffirmed the importance of their countries’ long-standing alliance. It also said Prayuth in turn had invited Trump to visit Thailand at a convenient time.

The White House statement about the call to Lee mentioned that “robust security cooperation and close collaboration on regional and global challenges” mark the two countries partnership.